Polymer blends and nonwoven articles therefrom

Abstract

This invention relates to a nonwoven article comprising a heterogeneous blend comprising: 1) from 60 to 99 weight percent of one or more semi-crystalline polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-crystalline polymer comprising propylene and from 0 to 5 weight % alpha-olefin comonomer (based upon the weight of the polymer), said semi-crystalline polymers each having a melting point between 100 and 170° C. and a melt flow rate of 2000 dg/min or less; and 2) from 1 to 40 weight % of one or more semi-amorphous polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-amorphous polymer comprising propylene and from 10 to 25 weight % of one or more C2 and or C4 to C10 alpha-olefin comonomers, said semi-amorphous polymers each having: a) heat of fusion of 4 to 70 J/g; b) a Melt Flow Rate of 0.1 to 2000 dg/min; c) an intermolecular compositional distribution as determined by thermal fractionation in hexane such that 85% by weight or more of the polymer is isolated as one or two adjacent, soluble fractions with the balance of the polymer in immediately preceding or succeeding fractions; and wherein each of these fractions has a wt % comonomer content with a difference of no greater than 20 wt % relative to the average wt % comonomer content of the copolymer; and d) an Mw/Mn of 1.5 to 4, and e) a propylene triad tacticity, as measured by 13 C NMR, of 75% or greater; where the blend of the semi-crystalline and semi-amorphous polymers comprises less than 5 weight % filler, based upon the weight of the polymers and the filler, and the blend has: i) an MFR greater than 10 dg/min; and ii) a Permanent Set of greater than 65% (as measured on a 125 mil thick molded part); and where the nonwoven article has a Hand of 40 g or less at a fabric basis weight of 35 gsm.

1. A nonwoven article comprising a heterogeneous blend comprising:
 1) from 60 to 99 weight percent of one or more semi-crystalline polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-crystalline polymer comprising propylene and from 0 to 5 weight % alpha-olefin comonomer (based upon the weight of the polymer), said semi-crystalline polymers each having a melting point between 100 and 170° C. and a melt flow rate of 2000 dg/min or less; and 
 2) from 1 to 40 weight % of one or more semi-amorphous polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-amorphous polymer comprising propylene and from 10 to 25 weight % of one or more C2 and or C4 to C10 alpha-olefin comonomers, said semi-amorphous polymers each having: 
 a) heat of fusion of 4 to 70 J/g; 
 b) a Melt Flow Rate of 0.1 to 2000 dg/min; 
 c) an intermolecular compositional distribution as determined by thermal fractionation in hexane such that 85% by weight or more of the polymer is isolated as one or two adjacent, soluble fractions with the balance of the polymer in immediately preceding or succeeding fractions; and wherein each of these fractions has a wt % comonomer content with a difference of no greater than 20 wt % relative to the average wt % comonomer content of the copolymer; and 
 d) an Mw/Mn of 1.5 to 4, and 
 e) a propylene triad tacticity, as measured by  13 C NMR, of 75% or greater; where the blend of the semi-crystalline and semi-amorphous polymers comprises less than 5 weight % filler, based upon the weight of the polymers and the filler, and the blend has: 
 i) an MFR greater than 10 dg/min; and 
 ii) a Permanent Set of greater than 65% (as measured on a 125 mil thick molded part); and 
 
       where the nonwoven article has a Hand of 40 g or less at a fabric basis weight of 35 gsm. 
     
     
       2. The article of  claim 1  wherein the semi-crystalline polymer comprises propylene and from 1 to 3 weight % of a C2 to C10 alpha olefin comonomer. 
     
     
       3. The article of  claim 2  wherein the alpha-olefin comonomer is selected from the group consisting of ethylene, butene, pentene, hexene, heptene, octene, nonene, and decene. 
     
     
       4. The article of  claim 2  wherein the alpha-olefin comonomer is selected from the group consisting of ethylene, butene, hexene, and octene. 
     
     
       5. The article of  claim 2  wherein the alpha-olefin comonomer is ethylene. 
     
     
       6. The article of  claim 1  wherein the semi-crystalline polymer comprises 0 weight % comonomer. 
     
     
       7. The article of  claim 1  wherein the semi-crystalline polymer has a melting point of 120 to 165° C. 
     
     
       8. The article of  claim 1  wherein the semi-crystalline polymer has a flexural modulus of between 1030 and 2070 MPa. 
     
     
       9. The article of  claim 1  wherein the semi-amorphous polymer comprises propylene and from 12 to 20 weight % of a C2 to C10 alpha olefin comonomer. 
     
     
       10. The article of  claim 9  wherein the alpha-olefin comonomer is selected from the group consisting of ethylene, butene, pentene, hexene, heptene, octene, nonene, and decene. 
     
     
       11. The article of  claim 9  wherein the alpha-olefin comonomer is selected from the group consisting of ethylene, butene, hexene, and octene. 
     
     
       12. The article of  claim 9  wherein the alpha-olefin comonomer is ethylene. 
     
     
       13. The article of  claim 1  wherein the semi-amorphous polymer has a percent crystallinity of between 2 and 25%. 
     
     
       14. The article of  claim 1  wherein the semi-amorphous polymer has a Mooney viscosity (1+4@125° C.) of 3 or more. 
     
     
       15. The article of  claim 1  wherein the semi-amorphous polymer has a melt flow rate of 5 to 2000 dg/min. 
     
     
       16. The article of  claim 1  wherein the semi-amorphous polymer has a melt flow rate of 20 to 1750 dg/min. 
     
     
       17. The article of  claim 1  wherein the heterogeneous blend has a heat deflection temperature of 40° C. or more as measured under 1.8 MPa of pressure. 
     
     
       18. The article of  claim 1  wherein the heterogeneous blend has a haze of 50% or less as measured on a 1 mm thick chip. 
     
     
       19. The article of  claim 1  wherein the blend further comprises a nucleating and or clarifying agent. 
     
     
       20. The article of  claim 19  wherein the blend has a haze of 20% or less as measured on a 1 mm thick chip. 
     
     
       21. The article of  claim 20  wherein the blend has a haze of 18% or less. 
     
     
       22. The article of  claim 20  wherein the blend has a haze of 16% or less. 
     
     
       23. The article of  claim 20  wherein the blend has a haze of 14% or less. 
     
     
       24. The article of  claim 20  wherein the blend has a haze of 12% or less. 
     
     
       25. The article of  claim 1  wherein the optimum bonding temperature of the heterogeneous blend is at least 5° C. lower than the optimum bonding temperature of the same blend, except that the semi-amorphous polymer is absent. 
     
     
       26. The article of  claim 25  where the optimum bonding temperature is at least 10° C. lower. 
     
     
       27. The article of  claim 25  where the optimum bonding temperature is at least 15° C. lower. 
     
     
       28. The article of  claim 25  where the optimum bonding temperature is at least 20° C. lower. 
     
     
       29. The article of  claim 25  where the optimum bonding temperature is at least 25° C. lower. 
     
     
       30. The article of  claim 25  where the optimum bonding temperature is at least 30° C. lower. 
     
     
       31. The article of  claim 1  wherein the blend has a permanent set of 85% or more. 
     
     
       32. The article of  claim 1  wherein the blend has a permanent set of 100% or more. 
     
     
       33. The article of  claim 1  wherein the blend has a permanent set of 125% or more. 
     
     
       34. The article of  claim 1  wherein the blend has a permanent set of 150% or more. 
     
     
       35. The article of  claim 1  wherein the nonwoven article has a fabric basis weight of 35 gsm or more, has a TD Peak Tensile load at optimum bonding of at least 5% greater than the TD Peak Tensile load of the same blend except that the semi-amorphous polymer is absent, and has an optimum bonding temperature at least 10° C. lower than the optimum bonding temp of the same blend except that the semi-amorphous polymer is absent. 
     
     
       36. The article of  claim 1  wherein the semi-amorphous polymer comprises from 12 to 20 weight % comonomer and is present at from 20 to 40 weight %, and wherein the article at 35 g/sq m basis weight has a hand value of 10 to 30 g, a transverse direction peak force at optimum bonding temperature greater than 5 g, a machine direction tear strength greater than 500 g, and an optimum bonding temperature 5° C. to 40° C. lower than that of the same article made from the same composition except that the semi-amorphous polymer is absent. 
     
     
       37. The article of  claim 36  wherein the comonomer is ethylene. 
     
     
       38. The article of  claim 1  wherein the semi-crystalline polymer has a melting point of 120 to 160° C. and a flexural modulus of 1030 to 2070 MPa; and the semi-amorphous polymer comprises 10 to 20 weight % comonomer, has a percent crystallinity of 2 to 25% and has a Mooney viscosity (1+4@125° C.) of 3 or more. 
     
     
       39. The article of  claim 1  wherein the heterogeneous blend further comprises a slip agent. 
     
     
       40. The article of  claim 1  wherein the heterogeneous blend further comprises from 50 ppm to 10 weight % of a slip agent, based upon the weight of the heterogeneous blend. 
     
     
       41. The article of  claim 40  wherein the slip agent is selected from the group consisting of amides having the chemical structure CH 3 (CH 2 ) 7 CH═CH(CH 2 ) x CONH 2  where x is 5 to 15. 
     
     
       42. The article of  claim 40  wherein the slip agent is selected from the group consisting of: erucamide, oleylamide, oleamide, and stearamide. 
     
     
       43. The article of  claim 1  wherein the heterogeneous blend further comprises from 50 ppm to 4000 ppm of a nucleating agent, based upon the weight of the total polymer present in the heterogeneous blend. 
     
     
       44. The article of  claim 1  wherein the article is packaging material. 
     
     
       45. The article of  claim 1  where the article is a package. 
     
     
       46. The article of  claim 1  where the article is a nonwoven web. 
     
     
       47. The article of  claim 1  where the article is a fabric. 
     
     
       48. The article of  claim 1  where the nonwoven is spunbonded. 
     
     
       49. The article of  claim 1  where the nowoven is meltblown. 
     
     
       50. The article of  claim 1  where the article is a surgical gown or drape. 
     
     
       51. The article of  claim 1  where the article is clothing. 
     
     
       52. The article of  claim 1  where the article is a diaper. 
     
     
       53. The article of  claim 50  where the article comprises a bactericidal agent. 
     
     
       54. The article of  claim 1  where the article is selected from the group consisting of: nonwoven fabrics, hook and loop fasteners, fabrics, garments, clothing, medical garments, surgical gowns, surgical drapes, diapers, training thermal insulation, first aid dressings, medical wraps, fiberfill, outerwear, bed quilt stuffing, furniture padding, filter media, scrubbing pads, wipe materials, hosiery, automotive seats, upholstered furniture, carpets, carpet backing, filter media, disposable wipes, diaper coverstock, gardening fabric, geomembranes, geotextiles, sacks, housewrap, vapor barriers, breathable clothing, envelopes, tamper evident fabrics, protective packaging, and coasters. 
     
     
       55. The article of  claim 1  wherein the heterogeneous blend has a continuous phase comprising the semi-crystalline polymer. 
     
     
       56. The article of  claim 1  wherein the heterogeneous blend has a discontinuous phase comprising the semi-amorphous polymer. 
     
     
       57. The article of  claim 1  wherein the heterogeneous blend has co-continuous phases of the semi-crystalline polymer and the semi-amorphous polymer. 
     
     
       58. The article of  claim 1  wherein the blend is formed into staple fibers prior to being formed into the non-woven article. 
     
     
       59. The article of  claim 58  wherein the staple fiber is crimped. 
     
     
       60. The fiber of  claim 59  wherein the staple fiber is 7 to 200 mm long. 
     
     
       61. A process to produce the nonwoven article of  claim 58 , the process comprising:
 1) blending a first component comprising from 60 to 99 weight percent of one or more semi-crystalline polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-crystalline polymer comprising propylene and from 0 to 5 weight % alpha-olefin comonomer (based upon the weight of the polymer), said semi-crystalline polymers each having a melting point between 100 and 170° C. and a melt flow rate of 2000 dg/min or less; and from 1 to 40 weight % of one or more semi-amorphous polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-amorphous polymer comprising propylene and from 10 to 25 weight % of one or more C2 and or C4 to C10 alpha-olefin comonomers, said semi-amorphous polymers each having: 
 a) heat of fusion of 4 to 70 J/g; 
 b) a Melt Flow Rate of 0.1 to 2000 dg/min; 
 c) an intermolecular compositional distribution as determined by thermal fractionation in hexane such that 85% by weight or more of the polymer is isolated as one or two adjacent, soluble fractions with the balance of the polymer in immediately preceding or succeeding fractions; and wherein each of these fractions has a wt % comonomer content with a difference of no greater than 20 wt % relative to the average wt % comonomer content of the copolymer; and 
 d) an Mw/Mn of 1.5 to 4, and 
 e) a propylene triad tacticity, as measured by  13 C NMR, of 75% or greater; where the blend of the semi-crystalline and semi-amorphous polymers comprises less than 5 weight % filler, based upon the weight of the polymers and the filler, and the blend has: 
 i) an MFR greater than 30 dg/min; and 
 ii) a Permanent Set of greater than 65% (as measured on a 125 mil thick molded part); and 
 2) extruding the blend composition to produce, finish, and wind a filament, then draw, finish, crimp, heat set and cut the filament into a staple fiber; and 
 3) forming the staple fiber into a non-woven fabric, where the nonwoven article has a Hand of 40 g or less at a weight of 35 gsm. 
 
     
     
       62. The process of  claim 61  wherein the staple fiber is 7 to 200 mm long. 
     
     
       63. A process to produce the nonwoven article of  claim 58 , the process comprising:
 1) blending a first component comprising from 60 to 99 weight percent of one or more semi-crystalline polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-crystalline polymer comprising propylene and from 0 to 5 weight % alpha-olefin comonomer (based upon the weight of the polymer), said semi-crystalline polymers each having a melting point between 100 and 170° C. and a melt flow rate of 2000 dg/min or less; with from 1 to 40 weight % of one or more semi-amorphous polymers (based upon the weight of the semi-crystalline and semi-amorphous polymers), each semi-amorphous polymer comprising propylene and from 10 to 25 weight % of one or more C2 and or C4 to C10 alpha-olefin comonomers, said semi-amorphous polymers each having: 
 a) heat of fusion of 4 to 70 J/g; 
 b) a Melt Flow Rate of 0.1 to 2000 dg/min; 
 c) an Mw/Mn of 1.5 to 4, and 
 d) a propylene triad tacticity, as measured by  13 C NMR, of 75% or greater; where the blend of the semi-crystalline and semi-amorphous polymers comprises less than 5 weight % filler, based upon the weight of the polymers and the filler, and the blend has: 
 i) an MFR greater than 30 dg/min; and 
 ii) a Permanent Set of greater than 65% (as measured on a 125 mil thick molded part); and 
 2) extruding the blend composition to produce, finish, and wind a filament, then draw, finish, crimp, heat set and cut the filament into a staple fiber; and 
 3) forming the staple fiber into a non-woven fabric, where the nonwoven article has a Hand of 40 g or less at a weight of 35 gsm. 
 
     
     
       64. The process of  claim 63  wherein the staple fiber is 7 to 200 mm long. 
     
     
       65. The process of  claim 63  wherein the intermolecular compositional distribution of the semi-amorphous polymer is such that 90% by weight or more of the polymer is isolated as one or two adjacent, soluble fractions with the balance of the polymer in immediately preceding or succeeding fractions; and wherein each of these fractions has a wt % comonomer content with a difference of no greater than 10 wt % relative to the average wt % comonomer content of the copolymer.